Production of ketones



Patented Mar. 30, 1943 T ED: S AT PRODUCTION or xarorms Alva C. jByr ns, Palos Verdes'Estates, Calif; as I '"sig'nor to UnioniOil Company or California, Los

' Angeles, Calif., a corporation or California,

applicationMarchi,1940, Serial N; 322,341 Y 7 Claims. (Cl- 260-593) No Drawing.

This invention relates to'processes for producing ketones and related compounds; The invention further resides in the production of new and novel ketones of distinctive odor useful as-solvents, chemical intermediates and as ingredients in perfumes.

In a more specific sense, the invention is con.- cerned with processes for selectively reacting organic'acid anhydrides with olefins, preferably in the presence of a mild catalytic agent such as, for example, anhydrous zinc chloride, to produce compounds of ketonic character which are readily recoverable in high yields from the reaction mass.

Heretoforeyit has been recognized that olefinswould react with organic* acid chlorides in the presence of anhydrous aluminum chloride to. produce chloroketones. Nenitzescu andGavat Annalen, vol. 519, page 260, 1935 observed that propylene would react with acetyl chloride in the =presence of a large excess of anhydrous alumi- 'num chloride to produce a chloroketonewhich could be subsequently condensed with benzene to form a phenyl pentanone as shown by the 191- lowing equation:

CI Is I I Cfi-CHzCOCI i" Likewise, it has been'shown by'Adams and Noller (Organic Synthesis, collective vol. 1, page anhydrous aluminum chloride toiormpacetophenone,- an -aralkyl ..ketone., In order to obtain 'maximum; yields of acetophenone it is necessary Aliphatic 105, John Wiley and Sons, 1932). that acetic an- 1 hydride will react with benzene in the presence or to use at least .two, mols of aluminum chloride Nageland Stirtonf (Industrial and Engineering Chemistry, vol. 26, page 1317, 1934) have demonstrated-that the reaction proceeds through, the

formation of acetyl chloride from the acetic anhydride and part of the aluminum chloride; and subsequent reaction of 'the'acetylchloridewith the benzene in. a manner typical of the well known Friedel and Crafts reaction, It is 'to be p ticularly noted in the last example that there is a copious evolution of hydrogen chloride as the reaction progresses. Furthermore, under relatively mild reaction conditions, mild catalysts, such as for example, anhydrous zinc chloride, will not cause the reaction to occur, possibly due to inability to form the acid chloride from the anhydride. -In=typical .Friedel and Crafts" reactions and variations thereof, such as the two for each molof acetic anhydride. Grogg'ins,"

catalyst. It is a further object to provide a proc:

ess for-producing'ketonic compounds by the com bination-of an olefin with an organic acid anhydride; in which axrelativelysmallproportion of catalyst to reactants is required and in which atleast a portion of: the catalyst is recoverable either unchanged or in useful form. r I I have now discovered that if an olefin is contacted with an organic acid anhydride under appropriate conditions, a chemical reaction occurs which may be represented by the following general equations:

Cyclo ketone carboxylacid anhydride ic acid In the foregoing equations, 11 and m represent integers, 11 having a value or 3 or higher and m having-a value of 5 or higher. R. represents a hydrocarbon radical. The hydrocarbon radicals present inthe acid anhydride may be the same, as they are in acetic anhydride',

or they may be different as in a mixed v,acid anhydride', such as cH3- -co o-co-c6m or they may combined in One radicalso 'asto ,givea'cyclic structure, such as is present rorjexample, in phthalic anhydride. and succinicanhydride. In the case of acid anhydridespf the latter type, the reaction results in the formation of a keto-acid as shown in u the following exemplary equation: x

0\ J I OHM! a loo-emu, I v COOH-f} sac. P a

I Eduction labove, represents the combination or ari' ole fi n er, the aliphatic "or. ethylene series of hydrocarbons with anorganic acid anhydride to form a ketone and an organic acid. Although I have found that any olefin of the aliphatic series of hydrocarbons will react with an organic i acid anhydride to produce aketonic compound under su'filciently rigorous conditions, I have iurther discovered that olefins having branched carbon chains and especially those having the 101- lowing configurations or structures which are converted into the following configurationsunder the conditions of the reaction, are particularly reactive andv will combine with an organic acid anhydride under relatively mild reaction conditions. a

'In the above structuralfonnulas, R represents either'a hydrogen atom or a hydrocarbon radical As typical examples of the'compounds representedby the above general formulas, the allowing tion to provide a process for producingnketones' under relatively mild reaction conditions by re acting organic acid anhydrides with olefins hav ingthe structuralconfigurations= a R=c=c ca= ca3 and 'R2C(CRa)-CH=CRa and preferably those having the structural configuration I where. R represents either a hydrogen atom or a hydrocarbon radical and preferably either hydro- .gen or an alkyl hydrocarbon radical and the various Rs may bethesame or difierent.

Equation 2 above represents the combinatiom of a cylclo-olefin lwithan acid anhydrideto produce a ketonic compound. Cyclic, olefins, such as for example, cyclohexene, cyclopentene and methyl cyclohexene, appear to condense with acidanhydrides to form ketones. as readily as do the branched chain olefinsof the aliphatic hydrocarbon series. Therefore, in general, the same reaction conditions and catalysts which cause formation of ketonic compounds from branched chain olefins of the aliphatic hydrocarbon series and acid anhydrides will likewise lead to the formationof ketones by theinteraction of cyclo-olefins and organic acid anhydrides. V

I have further discovered that the reaction is most readily carried out with those organic acid and the various R's may bethe sameor diiferent.

' for example, diisobutylene, is mixed at atmosanhydrides which are fluid at ordinary atmospheric temperatures. These comprise the acid anhydrldes of the lower molecular weight mono carboxylic acids of the aliphatic series, such as acetic anhydride, propionic anhydride, butyric anhydride, etc., andof the naphthenic acids. The structures of the latter compounds are not definitely known but they are believed to be mono-carboxylic acids containing one or more naphthenic hydrocarbon rings, the rings being either mono or hetero-cyclic. In many of the industrial applications of ketones, it appears that methyl ketones, that is, those possessing the CHaCO group, are particularly valuable. Such ketones can be obtained .by the processes of the present invention by employing acetic anhydride as the acid anhydride to be reacted with the olefin,'and this anhydride is, therefore, to be particularlypreferred. Where'it is desired to react those acid anhydrides which are solid at the usual atmospheric temperatures it is ordinarily necessary to employ an inert solvent as the reaction medium or conduct the reaction at a sufficiently elevated temperature to melt the acid anhydride- In addition to the foregoing, I have observed that if an olefin, particularly a branched chain olefin of the types described hereinabove, such as,

pheric temperature with an organic acid. anhydride, there is little or no evidence that any reaction occurs and in fact it is possible to separate the olefin from the anhydride substantially unchanged. However, if. a quantity of a mild catalyst, such as, for example, anhydrous zinc ch10- ride, is added to the mixture of olefin and acid anhydride at room temperature, it is immediately apparent that a reaction is occurring as is evidenced by the evolution of considerable-heat and fa marked change inthe odor of the material.

Closer examination of the mass reveals that aketone hasjbeen formed. Another catalyst which appears to induce .a similar type ,of reaction is concentrated sulfuric acid.

' I! anhydrous aluminum chloride is added to a mixture of olefin and acid anhydride at room temperature a reactionoccurs accompanied 'with ,evolution of hydrogen chloride, but the resultant product'aprpears to be a mixture ofmany differvent' compounds boiling over a wide range of temperatures with no particular compound being rormed in relatively large amount. This is-readily understandable in view of the known high activ'ityfof aluminum chloride and its ability to rupture as well as cause the formation of carbon' to carbon bonds. 7

It is an additional object of the present invention to produce ketones by reacting an olefin, preferably a branched chain olefin having one of the configurations described hereinabove, with an organic acid anhydride, preferably derived from one or the lower molecular weight. mono-carboxylic acids, said reactiorr-being conducted in the presence of a mild catalytic agent such as anhydrous zinc chloride and at atmospheric or somewhat elevated temperatures.

EXAMPLE 1 I Approximately 150 grams of anhydrous zinc chloride (technical, 94% pure, equivalent to 1 mol) was-added to 120 milliliters of acetic anhy- I the reaction mixture in order to maintain the v dride (equivalent to L2 mols). Most of the zinc chloride dissolves in the anhydride to form a fluid mass, heat being evolved and a complex of the two' compounds possibly being formed. The temperature of the mass is preferably maintained in the neighborhood of 100 F. throughout the experiment and in any event it is not to exceed 200 F. since at higher temperatures acetic anhydride appears to decompose to a tarry mass in the presence of zinc chloride. Reaction will occur at temperatures considerably below 100 F. but the formation of the ketone is slow and intimate contacting of the acetic anhydride-zinc chloride mixture with the olefin is more difilcult to obtain because of the decreased fluidity of the reaction mass. V

After most of the zinc chloride had dissolved in the acetic anhydride and the temperature had been adjusted to approximately 100 F., 150 milliliters of commercial diisobutylene (equivalent to 1 mol) was added over a period. of two hours and intimately mixed with the acetic anhydride-zinc chloride complex. Considerable heat is evolved during the reaction and it was necessaryto cool temperature in the neighborhood of 100 F. I Commercial diisobutylene is a mixture of two principal isomers: 2,4,4-trimethyl pentene-l and 2,4,4-trimethyl pentene-Z, comprising about 80% and 20% of the commercial product, respectively.

After all of the diisobutylene had been added,

taining zinc chloride and acetic acid and an upper brownish-colored phase constituting the crude ketone. In passing it should be particularly noted that at no stage in the process was there any evidence of the formation of hydrogen chloride, thus distinguishing this reaction from the usual Friedel-Crafts reactions.

milliliters was finally fractionated under reduced pressure to produce a practically colorless mobile liquid of narrow boiling range and distinctive pleasant odor. The crude ketone can be fractionated at atmospheric pressure but the resultant material is yellowish in color, possibly due to the presence of small amounts of decomposition products. Steam distillation of the crude ketone can be resorted to if desired.

The pure ketone constituted approximately 85% of the recovered crude ketone phase, the remaining 15% being principally unreacted diisobutylene together with a small amount of high I boiling material, possibly tetraisobutylene. The

pure ketone exhibited the following physical properties: I c 7 Specific gravity, 60/ 60 F 0.848 Refractive index 1.452 Boiling point, F. (uncorr.)' 375 Boiling point, F.l 18 mm. (uncorn) 1'73 Quantitative analysis of the pure ketone indicated that'it had the following percentage composition; carbon 77.60%, hydrogen 11.92%, and oxygen 10.40%. These values are in good agreement with those of the expected empirical formula 010E180 which has the following percentage composition; carbon 77.87%, hydrogenv 11.76%

and oxygen 10.37%. These results indicate that the reaction takes place in accordance with the following equation: I

ketone acetic acid C a m Diisobutylene acetic anhydride to form semi-carbazones,-

the latter in general being easily purified solids,

' of semi-carbazide hydrochloride to which had The two phases were separated, and "the upper washed twice with water and finally treated with dilute sodium carbonate solution toremove the last traces of acetic acid. The'ketone formed is or the water washings.

The washed crude ketone, amounting. to 146 been added an excess of sodium acetate. I vA solid precipitate separated indicating the formation of the semi-carbazone and demonstrating that the compound obtained is a ketone. The

melting point of the separated and purified semicarbazone'is 334-336 F. (uncorrJu Another reaction which ischaracteristic of the CHaCO group or groups which will ready yield this configuration under the conditions of the test is the Haloform reaction, an improved modification of whichis described by Fuson and Tullock, Journal of the American Chemical Society, vol. 56, page 1638 (1934). The test depends upon the reaction of sodium hypoiodite with compounds containing the CH'sCO group to' form iodoform. The narrow boiling fraction obtained from the distillation of the crude ketone was tested in accordance with the description of Fuson and Tullock, noted above, and iodoform positively identified in the reaction products. ,This evidence taken in conjunction with that for the formation of a semi-carbazone definitely indictates that the compound isolated contains a readily, it is believed that the ketone isolated .related structures;

i the catalyst;

the aboveiexperiment is approximately 65-mol percent and after making allowance for unre-' milliliters of commercial diisobutylene (equivalent to t mol) subsequently added slowly. After allowing the reaction to complete itself, 5 grams of crystalline complex and 22 milliliters (equivalent to 0.12 mols) of ketone, CwHraO. were recovered. This indicates that each moi of zinc chloride is capable of causing the formation of at least four mols of ketone.

. Exsmrnz 4 7 Three milliliters of 94% H2804 was mixed with 30 milliliters of acetic anhydride, the mixture cooled to 'roomtemperature and 30 milliliters of commercial diisobutylene added. After allowing one hour for the reaction to complete itself, themixture was hydrolyzed with water and 28 milliliters of a. separated ketone phase acted diisobutylene recovered, it is evident'that there is an appreciable amount of diisobutylene unaccounted for. The aqueous phase separated from .the crude ketone after hydrolysis of the reaction product was cooled to a temperature of approximately 35. F. A crystalline solid of slightly: yellowish color precipitated and was sep-.

arated from the supernatant liquid by filtration. Precipitation of the crystalline material can likewise-be accomplished through concentration of the solution by partial evaporation. This crystalline product appears to be a complex comprising zinc chloride and a ketone having four:

teen carbon atoms; This crystalline complex reacts with hydroxylamine to form a crystalline 1 oxime with the liberation of zinc chloride and with dilute ammonia to form an imine boiling at 114.5 C. at a pressure of mm. Oi particular interest is the fact thatan aqueous solution of the crystalline complex reacts readily with aniline at room t'emperatur'e to form a Schiils base type of compound.

v i Exmru: 2 i V ,The yields of ketones realizable from any given set of ;reactance' is apparently markedly afl'ected by the order in winch-the'reactants are added into the reaction vessel. In an experiment* comparable to Example 1-, 4350 grams of anrecovered, of which approximately 70% estimated to be ketoneCmHiaO.

I Exsmrmh I :Twenty grams of anhydrous zinc chloride was added to 20 milliliters of acetic anhydride and 20 milliliters of cyclohexene (obtained from. Eastman) subsequently added. After hydrolysis of the reaction mixture and fractionation of the ketone layer, 18 milliliters of an oil was obtained which hadan odor similar to that of acetophenone. The oil was identified as a ketone.

' Exam ne 6 A quantityof 2-ethylhexanol (obtained from was ' Carbide and Carbon Chemicals Corporation) was dehydratedto give a mixture of ,oc'tylenes. This mixture of octyleneswas reacted with acetic anhydride in the'presence of zinc chloride in the mannerputlined in the previous examples. The hydrol'y'zate from the reaction mass was comprised principally of ketones.

, The foregoing exemplary'description of. my invention'is not tobe considered as limiting since many variations may be made within the scope hydrous zinc chloride (technical, 94% pure) was mixed with 4600"milliliters"of commercialdiiso- 'butylene and 3150 milliliters of acetic anhydride subsequentl added slowlyto the mixture. After allowing sufllcient timefor' the reaction to complete itself, the mixture was hydrolyzed with water inthe manner'previously described inExample 1 above. Approximately .3870 millilitersof crude ketonewas 'obtalnedand on fractionation of thematerial, it was found that there was no unreacted' diisobutylene present, the product being comprised'essentially of 50% of the, desired ketone and 50% of a 'highboiling hydrocarbon,

apparently tetraisobutylene. The molal the desired ketone was only 26.5%".

that the most desirableprocessfor obtaining maximum yield'of ketones comprisesadmixture of the organic acid anhydride-with thecatalyst yieldof.

- 00 Since mild catalysts such as zinc chloride vwill catalyze the polymerization of oiefins, it-appears andsubsequent slow addition of the olefin to the I anhydride-catalyst mixture inorder to avoldany large excess of unreacted-olefin incontact with 'Fivegrams of anhydrous zinc chlorideiequiv alent to 4 mol) was admixed with'35 milliliters of acetic anhydride (equivalent to V mol) and 50 of the following claims by those skilled in the art without departing gfrom the spirit thereof.

I claim:

1 A method for'the production of ketones which comprises reacting an olefin with an organic acid anhydride in the presence of anhye drous zinc chloride.

,2. A method for the production of ketones which comprises reacting acetic anhydride with di-isobutylenes in the presence of zinc chloride as a, catalyst.

3. A method for producing ketones which comprises reacting acetic anhydride with di-isobutylem in the presence of zinc-chloride-as a catalyst, at a temperature ofv about F. to about F.

4, A ketone having the structural formula:

CH3 CH3, I O

' Cm-Jz-cn: Ami-41m on. i

5.- A ketone havingthe structural formula:

- i on, on, v

j ,om-to n- =03,

6. A method according to claim -1 in which the olefin employed is a' 'cyclo-olefin. V

7. Amethod according to claim 1 in which the olefin employed is a normally liquid olefin.

, ALVA c. BYRNS. 

